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To quantify the drug-drug interactions between dabigatran etexilate (DE) and proton pump inhibitors (PPI) and in particular the role of P-gp activity modulation. In the first part of the study, efflux ratios of DE were evaluated using the caco-2 cell line in the presence of pantoprazole, omeprazole, rabeprazole, lansoprazole and ciclosporin A (positive control). The two PPI that reduced the efflux ratio of dabigatran to the greatest and least extent, respectively, were used during the second part of the study, comprising a single-centre, randomised, open-label study with an incomplete Latin square design. Nine healthy volunteers received DE (150 mg) alone, DE (150 mg) with the first PPI and DE (150 mg) with the second PPI in randomised sequence. Dabigatran plasma concentration and thrombin time were measured in blood samples withdrawn at 11 time points after each treatment. Models were built using a nonlinear mixed-effect modelling approach. Omeprazole and rabeprazole were the two PPI that reduced the efflux ratio of DE least and most, respectively. The PK model was based on an inverse Gaussian absorption process with one compartment. The relationship between dabigatran concentration and thrombin time was considered linear. Some PK profiles had dramatically low concentration values due to poor absorption. These profiles were clustered using a between subject model mixture with interoccasion variability. The concomitant administration of PPI did not significantly change dabigatran pharmacokinetics. DE is subject to high absorption variability, precluding evaluation of the effect of PPI on its pharmacokinetics., (© 2015 Société Française de Pharmacologie et de Thérapeutique.)

Thromboprophylaxis with low molecular weight heparin or fondaparinux is associated with a 50% reduction in the risk of venous thrombo-embolism (VTE) in medical patients. Thromboprophylaxis is indicated in the prevention of VTE in medical patients at risk of VTE. Extended thromboprophylaxis with apixaban is associated with a greater reduction in VTE events but also with an increase in bleeding events when compared to standard therapy with enoxaparine. Extended thromboprophylaxis with rivaroxaban is associated with a greater reduction in VTE events but also with an increase in bleeding events, when compared to standard therapy with enoxaparine. Rivaroxaban and apixaban are currently not indicated in medical prophylaxis., (Copyright © 2013 Elsevier Masson SAS. All rights reserved.)

Aim: The aim of this study was to develop a PK/PD model to assess drug-drug interactions between dabigatran and P-gp modulators, using the example of clarithromycin, a strong inhibitor of P-gp., Methods: Ten healthy male volunteers were randomized to receive in the first treatment period a single 300 mg dose of dabigatran etexilate (DE) and in the second treatment period 500 mg clarithromycin twice daily during 3 days and then 300 mg DE plus 500 mg clarithromycin on the fourth day, or the same treatments in the reverse sequence. Dabigatran plasma concentration and ecarin clotting time (ECT) were measured on 11 blood samples. Models were built using a non-linear mixed effect modelling approach., Results: The best PK model was based on an inverse Gaussian absorption process with two compartments. The relationship between dabigatran concentration and ECT was implemented as a linear function. No continuous covariate was associated with a significant decrease in the objective function. The concomitant administration of clarithromycin induced a significant change only in DE bioavailability, which increased from 6.5% to 10.1% in the presence of clarithromycin. Clarithromycin increased peak concentration and AUC by 60.2% and 49.1% respectively., Conclusion: The model proposed effectively describes the complex PK of dabigatran and takes into account drug-drug interactions with P-gp activity modulators, such as clarithromycin., (© 2012 The Authors. British Journal of Clinical Pharmacology © 2012 The British Pharmacological Society.)

Recent data on lower-limb superficial-vein thrombosis (SVT) may substantially impact its clinical management. Particularly, the clear confirmation that SVT is closely linked to deep-vein thrombosis (DVT) or pulmonary embolism (PE) highlights the potential severity of the disease. DVT or PE is diagnosed in 20-30% of SVT patients. Moreover, clinically relevant symptomatic thromboembolic events complicate isolated SVT (without concomitant DVT or PE at diagnosis) in 4-8% of patients. For the first time, an anticoagulant treatment, once-daily 2.5 mg fondaparinux for 45 days, was demonstrated to be effective and safe for preventing these symptomatic thromboembolic events in patients with lower-limb isolated SVT in the randomized, placebo-controlled CALISTO study. More recent data from another randomized trial support these findings. New recommendations on the management of SVT patients, including complete ultrasonography examination of the legs and, in patients with isolated SVT, prescription of once-daily 2.5 mg fondaparinux subcutaneously for 45 days on top of symptomatic treatments, may be proposed, wherever the cost of fondaparinux is acceptable. Superficial-vein thrombosis (SVT) of the lower limbs has long been regarded as a benign, self-limiting disease, expected to resolve spontaneously and rapidly, and requiring only symptomatic treatments [1,2]. However, the perception of this disease is now changing with the recent publication of data indicating its potential severity [3] and showing for the first time the benefit of a therapeutic strategy based on the administration of an anticoagulant treatment [4]. The overall management of this frequent disease therefore needs to be reconsidered., (Copyright © 2012 Elsevier Ltd. All rights reserved.)